18272218 has 4 divisors (see below), whose sum is σ = 27408330. Its totient is φ = 9136108.

The previous prime is 18272207. The next prime is 18272239. The reversal of 18272218 is 81227281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81227281 = 3823 ⋅21247.

It can be written as a sum of positive squares in only one way, i.e., 18258529 + 13689 = 4273^2 + 117^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 18272218.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4568053 + ... + 4568056.

Almost surely, 2^18272218 is an apocalyptic number.

18272218 is a deficient number, since it is larger than the sum of its proper divisors (9136112).

18272218 is an equidigital number, since it uses as much as digits as its factorization.

18272218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9136111.

The product of its digits is 3584, while the sum is 31.

The square root of 18272218 is about 4274.6015018947. The cubic root of 18272218 is about 263.3886700279.

Adding to 18272218 its reverse (81227281), we get a palindrome (99499499).

The spelling of 18272218 in words is "eighteen million, two hundred seventy-two thousand, two hundred eighteen".